From: Daniel Cisco Group Study (danielcgs@imc.net.au)
Date: Sat May 10 2003 - 01:38:43 GMT-3
AS Path length is shorter via your confed peer AS:
(65000) 1581 1776 --> BEST
vs
1771 1581 1776 --> longer AS-PATH length
Confed ASs are not considered in path length
Daniel
-----Original Message-----
From: Richard Davidson [mailto:rich@myhomemail.net]
Sent: Saturday, 10 May 2003 06:30
To: groupstudy
Subject: confederation path selection and Admin distance?
confederation path selection and Admin distance?
I have a confederation issue. I can't figure out why
my router is selecting the iBGP confederation peer as
apposed to my eBGP peer.
My router has to paths. I think, before the path
selection algorithm the router looks at admin
distance. Well the route that is being injected has a
distance of 200 and the route that is not has a
distance of 20. I brought down the link to the iBGP
confederation peer and the eBGP neighbor with a
distance of 20 came up.
See attached:
router bgp 65001
no synchronization
bgp log-neighbor-changes
bgp confederation identifier 100
bgp confederation peers 65000
neighbor 172.16.101.1 remote-as 65001
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.103.1 remote-as 65000
neighbor 172.16.103.1 ebgp-multihop 255
neighbor 172.16.103.1 update-source Loopback0
neighbor 172.30.4.10 remote-as 1771
r4#sib 140.10.1.0
BGP routing table entry for 140.10.1.0/24, version 99
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
172.16.101.1 172.30.4.10
(65000) 1581 1776
172.40.10.10 (metric 200) from 172.16.103.1 (172.16.103.1)
Origin IGP, localpref 100, valid, confed-external, best
1771 1581 1776
172.30.4.10 from 172.30.4.10 (192.88.1.1)
Origin IGP, localpref 100, valid, external
r4#i | i 140.10.1.0
B 140.10.1.0 [200/0] via 172.40.10.10, 00:27:50
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